Q: Which equation correctly relates the mass of a polypeptide to its number of amino acids, given that the average mass of an amino acid is 110 Da?

$$\text{Mass (Da)} = \text{Number of amino acids} \times 110$$

Question 1

Which of the following best describes the primary structure of a protein?

Accepted Answer

The sequence of amino acids joined by peptide bonds in a straight chain

Question 2

A mutation in the gene encoding hemoglobin results in sickle cell disease. What is the molecular basis for this disease?

Accepted Answer

A single amino acid substitution in the primary structure alters the protein's function

Question 3

Which type of bond is primarily responsible for stabilizing the alpha helix and beta pleated sheet structures in proteins?

Accepted Answer

Hydrogen bonds

Question 4

Collagen is a structural protein that strengthens skin, bones, and tendons. Which feature is most critical for its tensile strength?

Accepted Answer

Its composition of three helical polypeptides coiled around each other

Question 5

Which of the following amino acids is essential and must be obtained from the diet?

Accepted Answer

Leucine

Question 6

A protein is exposed to high temperature and extreme pH. What is the most likely outcome?

Accepted Answer

The protein will undergo denaturation, losing its secondary, tertiary, or quaternary structure

Question 7

Which of the following best explains why prion diseases are unique among infectious diseases?

Accepted Answer

Prions are infectious particles composed only of protein, lacking nucleic acid

Question 8

Which chemical reaction occurs when two amino acids join to form a dipeptide?

Accepted Answer

Dehydration synthesis, resulting in the release of water

Question 9

A protein's tertiary structure is stabilized by several types of interactions. Which of the following is NOT typically involved in stabilizing tertiary structure?

Accepted Answer

Peptide bonds

Question 10

Which of the following is a function of globular proteins?

Accepted Answer

Catalyzing biochemical reactions as enzymes

Question 11

A patient presents with brittle bones due to a defect in type I collagen. What is the most likely cause?

Accepted Answer

A mutation in the gene encoding collagen

Question 12

Which equation correctly relates the mass of a polypeptide to its number of amino acids, given that the average mass of an amino acid is 110 Da?

Accepted Answer

$$	ext{Mass (Da)} = 	ext{Number of amino acids} 	imes 110$$

Question 13

Which of the following statements about protein quaternary structure is correct?

Accepted Answer

It is formed by interactions among multiple polypeptide chains

Question 14

Which of the following is a consequence of protein denaturation in the human body?

Accepted Answer

Loss of biological function due to unfolding and change in shape

Question 15

Which of the following best explains why a diet lacking in essential amino acids can lead to protein malnutrition, such as Kwashiorkor?

Accepted Answer

Essential amino acids must be obtained from the diet because the body cannot synthesize them

Question 16

Which of the following bonds is formed specifically between the sulfur atoms of two cysteine residues?

Accepted Answer

Disulfide bridge

Question 17

A protein is found to have both alpha helix and beta pleated sheet regions. What does this indicate about its structure?

Accepted Answer

It has multiple types of secondary structure within a single polypeptide

Question 18

Which of the following is NOT a function of proteins in the human body?

Accepted Answer

Storing genetic information

Question 19

Which of the following factors can disrupt the secondary, tertiary, or quaternary structure of a protein, leading to denaturation?

Accepted Answer

Changes in pH, temperature, or exposure to chemicals

Question 20

Which of the following statements about prion diseases is correct?

Accepted Answer

They involve misfolded proteins that can induce misfolding in normal proteins

9-Proteins: Structure, Function, and Clinical Relevance in Cell Biology

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